Various rubber materials and plastic materials have been used for the insulator coating of a wire or a cable. Exemplary rubber materials include natural rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, styrene butadiene rubber, butadiene acrylonitrile copolymer, ethylene propylene diene rubber, butyl rubber, polyisoprene, silicone rubber, fluororubber, and fluorine-containing elastomeric copolymer (for example, vinylidene fluoride-hexafluoropropene bromide copolymer, vinylidene fluoride-hexafluoropropene bromide-tetrafluoroethylene copolymer, vinylidene fluoride-pentafluoropropene bromide copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, tetrafluoroethylene-propylene copolymer, and tetrafluoroethylene-propylene-vinylidene fluoride copolymer), and exemplary plastic materials include polyethylene, polypropylene, polyvinyl chloride, and polyamide.
When an inorganic filler is blended with such rubber or plastic, the inorganic filler does not bond with the rubber or plastic due to the poor wetting of the boundary between the rubber or the plastic and the inorganic filler, and the mixture suffered form drastic loss of moisture resistance. In addition, when the inorganic filler was blended at a high content, the inorganic filler suffered from poor dispersion, and this resulted in the drastic loss of the mechanical properties.
Treatment of the inorganic filler surface with a silane coupling agent such as vinyltriethoxysilane or tris(methoxyethoxy)vinylsilane has been proposed as an attempt to improve the moisture resistance and the mechanical properties. Such surface treatment with the silane coupling agent, however, suffered from the drawback of insufficient moisture resistance and mechanical properties due to the insufficient surface treating effect due to the volatilization of the surface treating agent and insufficient hydrophobicity.
As an alkoxy group-containing silicone composition having vinyl groups and alkyl groups, JP-A 5-194544 discloses a straight and cyclic siloxane or siloxane oligomer mixture represented by the following formulae I and II:
wherein m is an integer of 0 to 8, n is an integer of 2 to 8, and R comprises vinyl group, methoxy group and/or ethoxy group, and/or an alkyl group, an isoalkyl group, or a cycloalkyl group of 1 to 18 carbon atoms, with the proviso that at least one vinyl group per silicon atom is present, the molar ratio of vinyl group to alkoxy group is 1:1 to 1:8, and the molar ratio of vinyl group to alkyl group is 1:0 to 1:8 for the crosslinking agent of the insulator material used for the cable. However, this publication does not disclose the use of such compound for the treatment of the inorganic filler in order to improve the moisture resistance. In addition, even if such compound were used for the treatment of the inorganic filler, improvement of the moisture resistance would be poor since this compound contains too much alkoxy groups in relation to vinyl group. Accordingly, further improvements have been awaited.
Other prior art documents include the following documents 2 to 6.
Citation ListPatent Document 1:JP-A 5-194544Patent Document 2:JP-A 5-239359Patent Document 3:JP-A 2001-64452Patent Document 4:JP-A 2001-114945Patent Document 5:JP-A 2002-513427Patent Document 6:JP-A 2005-248068